Are you talking about current crown prince or ex-crown prince??
ex-crown prince
Then I will disagree with you. From raws it's easy to see - the cheerful twin and ex crown prince are totally 100% just half brothers. He avoided serious twin because he made ex crown prince uncomfortable with his thirsty staring.
Also, ex crown prince just generally good person and totally not suitable for imperial schemes, that's how he got framed and deposed (〜￣△￣)〜
I think what @firefudger meant was that the ex crown prince should've known the consequences of his action by sending that letter and the current crown prince is doing all that to help him hence putting himself in a vulnerable position yet shao qi didn't understand him. And considering he was once a crown prince we would have expected him to be smart enough to realise.
I mean, ex crown prince is just too good/stupid for imperial drama. In later chapters you'll see more hints for bigger scheme and how this ex crown prince managed to get in this, and what role that/those letter(s) play ╮(￣▽￣)╭
Ahhh I see!! Were you reading the raws??
Found in earlier comments, somebody linked two sources(づ￣ ³￣)づ
Why did he had to fall for an innocent idiot? Like, he's putting hisself into danger to save him, and he doesn't even get this. And he was supposed to be the crown prince. Shouldn't he be able to have a better understanding of characters if he was supposed to become an emperor?